COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2418

                                      Konkoly Observatory
                                      Budapest
                                      18 October 1983

                                      HU ISSN 0374-0676



                INACTIVE STATE OF MV LYRAE



 The cataclysmic variable MV Lyrae is a candidate for a class of polars
(Vojkhanskaya et al., 1978, Vojkhanskaya and Mitrofanov, 1980). But unlike
other AM Herculis-type objects the polarization of MV Lyrae is very small,
its variations are not correlated with brightness changes (Efimov and
Shakhovskoy, 1980). The system is identified with an X-ray source H 1901+43
(Mason et al., 1979).
The investigation of archive plates of Sonneberg (Wenzel, 1980) and Moscow
and Odessa collections (Andronov and Shugarov, 1982) shows that from the
beginning of this century MV Lyrae was mainly in its high state (B<=14m). 
Inactive states lasting from several months to a year have a tendency to
gather, the interval between them may be as long as 17 years.

 In 1979 the system's brightness fell from 13.5m to 18m (Romano and Rosino
1980). The decline lasted for 40-60 days; this may be compared with the value
for AM Herculis (Andronov et al., 1983).
 Observations were taken with the 50-cm reflector and 40-cm astrograph of
the Southern Station of Sternberg State Astronomical Institute and the 45-cm
telescope of Odessa Astronomical Observatory. We used the B-magnitudes of
comparison stars taken from Andronov and Shugarov (1982). The 1979-1982 light
curve is shown in Figure 1.
 In the inactive state one can observe flares with an amplitude of 3m
lasting 1-2 months- similar in appearance to the photometric behaviour of
cataclysmic variable V 794 Aquilae (Petrochenko and Shugarov, 1982). In
addition, the mean brightness may undergo changes of 0.3m when B~~17m and
1.2m when B~~16m. We note that the present inactive state is not only the
deepest, but the longest as well, compared with other detected minima. Recent
observations show that MV Lyrae is now faint. On 2 May 1983 the brightness
was about 17.5m (not shown in Figure 1).
 If, as Robinson et al. (1981) suggested, we see the binary system entering 
the 2-3 hour period gap, it is unlikely that MV Lyrae will return to its
practically stationary active state for some 10^9 years.


                           [FIGURE 1]

 Figure 1   The 1979-1982 light curve of MV Lyrae. Filled squares 
          correspond to the observations of Romano and Rosino (1980)


 Individual light curves in the 1981-1982 inactive state are shown in
Figure 2. The amplitude of brightness changes may reach 1.2m which is really
greater than the values of 0.1m - 0.5m obtained for the active (B ~~ 12.5m) state
(Walker, 1954).
There is an interesting feature on the light curve when B = 17.3m. Sometimes 
one may observe "stationary" states lasting 2-3 hours that were detectable 
from our data and the results of photoelectric study (Robinson et al.,
1981).
 Photographic observations cannot be fitted on one light curve with a
spectroscopic period of 0.1336d (Schneider et al., 1981), but the time-scale
of brightness variations is not in disagreement with this value. If the
orbital inclination is small (i~~14deg) (Schneider et al., 1981), possible
orbital variations may be saturated by fluctuations connected with the
system's instability. The statistical amplitude increase in the inactive
state compared with the active state may be attributed to accretion flow 


                             [FIGURE 2]

        Figure 2   Individual light curves of MV Lyrae


instabilities when the relative contribution of separate inhomogeneities to
the luminosity increases. If accretion is completely reduced the luminosity
will decrease and variability disappears. Though, as one might expect, separate
inhomogeneities may penetrate from the secondary's envelope through the inner
Lagrangian point to the primary's Roche lobe. In this case separate flares
might be observed on the light curve.





            I.L. ANDRONOV
           Odessa Astronomical
           Observatory, USSR



            S.Yu. SHUGAROV
          P.K. Sternberg State
          Astronomical Institute
          Moscow, USSR





References:

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   Yu.B., 1983, Problemy kosmicheskoj fiziki, Kiev, 18, 98 [BIBCODE 1983PrKFi..18...98A ]
Andronov, I.L., Shugarov, S.Yu., 1982, Astr.Tsirk. No. 1218, 3 [BIBCODE 1982ATsir1218....3A ]
Efimov, Yu.S., Shakhovskoy, N.M., 1980, Izv.Crim.Astr.Observ. 61, 120
Mason, K.O., Kahn, S.M., Bowyer, C.S., 1979, Nature 280, 5723, 568 [BIBCODE 1979Natur.280..568M ]
Petrochenko, L.N., Shugarov, S.Yu., 1982, Astr.Tsirk. No. 1230, 3 [BIBCODE 1982ATsir1230....3P ]
Robinson, E.L., Barker, E.S., Cochran, A.L., Cochran, W.D., Nather, R.E.,
   1981, Astrophys. J. 251, 611 [BIBCODE 1981ApJ...251..611R ]
Romano, G., Rosino, L., 1980, I.B.V.S. No. 1776
Schneider, D.P., Young, P., Shectman, S.A., 1981, Astrophys. J. 245, 644 [BIBCODE 1981ApJ...245..644S ]
Vojkhanskaya, N.F., Gnedin, Yu.N., Efimov, Yu.S., Mitrofanov, I.G.,
   Shakhovskoy, N.M.,1978, Astron.Zhurn.Pis'ma 4, 6, 272 [BIBCODE 1978SvAL....4..148V ]
Vojkhanskaya, N.F., Mitrofanov, L.G., 1980, Astron.Zhurn.Pis'ma 6, 3, 159 [BIBCODE 1980SvAL....6...87V ]
Walker, M.F., 1954, Publ.Astron.Soc.Pacif. 66, 71 [BIBCODE 1954PASP...66...71W ]
Wenzel, W., 1980, Mitt.Veranderl.Sterne 8, 10, 172